Hi,
I am trying to run the Freertos demo for at90can128 on IAR compiler. I made some changes related to uart and timer registers accordying to the documentation. I try to run a board with avrstuido and some createtasks (those related to serial port on comtest.c) return errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY. The flash led task works ok...
Does anyone have some kind of solution or suggestion for this problem?

Where did you get the at90can128 port from? Seems you want to increase the amount of heap space you have. Look at the configTOTAL_HEAP_SIZE definition in FreeRTOSConfig.h.